2018 Volume 49 Issue 2 Pages 53-58
Introduction: Drooling is a common problem in patients with chronic neuromuscular diseases. Several studies have proposed transdermal administration of scopolamine for alleviation of this problem. At present, no transdermal formulation of scopolamine has been approved in Japan, and an in-house ointment formulation is usually used to control drooling in patients with disabilities. However, there is insufficient evidence to support the clinical use. The aim of this study was to perform an exploratory assessment of the pharmacokinetics and pharmacodynamics of a single dose of scopolamine ointment applied to the postauricular area in healthy subjects.
Methods: In this randomized, placebo-controlled, double-blind, single-dose, two-way crossover study, scopolamine ointment spread on an adhesive plaster (0.1g/2.0 cm2 ) was applied to the postauricular area for 24 h in 10 healthy subjects. Blood and urine samples were collected up to 48 h after the application. The concentration of scopolamine was measured by liquid chromatography-tandem mass spectrometry. The volume of saliva secreted, subjective salivary secretion assessed on a visual analog scale, and heart rate variability were measured to determine the pharmacodynamics of scopolamine.
Results: The plasma concentration of scopolamine increased slowly, reaching the maximum level (12.0±6.3 pg/mL) approximately 12 h after application of scopolamine ointment, and the level was maintained up to the last observation conducted 24 h after removal of the ointment. No apparent pharmacodynamic changes were observed.
Conclusions: The plasma concentration of scopolamine was maintained at low level, even after removal of the ointment. Pharmacological effects were not evident in healthy subjects. The current study indicates that further research is required to explore pharmacokinetics and the effects of multiple treatment doses in patients.
